Lamp energizing system



Nov. 7, 1967 F. P. EPPERT 3,351,809

LAMP ENERGIZING SYSTEM Filed Nov. 5, 1965 19 ,mw 55g" agay United States Patent C) 3,351,809 LAMP ENERGIZING SYSTEM Franklin P. Eppert, Danville, lll., assignor to General Electric Company, a corporation of New York Filed Nov. 5, 1965, Ser. No. 506,562 4 Claims. (Cl. 315-185) The invention relates to a lamp energizing system, and particularly to a system for energizing one selected set of a plurality of sets of serially connected gaseous discharge lamps.

Gaseous discharge lamps, particularly fluorescent lamps, are frequently used in signs and displays for illumination or for various lighting effects. Such signs and displays frequently require a sequence in which one set of fluorescent lamps is turned on, followed by the one set being turned off and a second set of fluorescent lamps being turned on. Then, the second set is turned off, and a third set of uorescent lamps is turned on. Additional sequences may be provided, the number depending on the number of sets of fluorescent lamps in the sign or display. Each of the sets may have any number of lamps in accordance with the sign or display desired. Previously, various arrangements have been used for energizing and deenergizing the lamps. Such arrangements have included a separate ballast for each lamp or for each set of lamps, with the separate ballasts being energized as desired. However, such arrangements are relatively expensive because where a large number of lamps or sets of lamps .are to be energized and deenergized, there have been a correspondingly large number of ballasts needed. Also, the separate ballasts have generally included means for heating the lamp filaments or cathodes. Such arrangements may cause the sequence of turningone set of lamps oft and another set of lamps on to be relatively slow, because the lamp cathodes require a finite time to reach their operating temperature.

Accordingly, an object of the invention is to provide an improved system for energizing and deener-gizing a plurality of sets of gaseous discharge lamps.

Another object of the invention is to provide a system that energizes `and deenergizes a plurality of sets of fluorescent lamps with a single ballast.

Another object of the invention is to provide a system that energizes and deenergizes a plurality of sets of uorescent lamps relatively quickly.

Another object of the invention is to provide a system for energizing and deenergizing a plurality of sets of fluorescent lamps, the system having a single ballast and a plurality of heater windin-gs constantly energizing the lamp cathodes, with a switching arrangement for connecting the desired setl of lamps to the ballast at a given time and quickly turning on the sets of lamps.

Briefly, these and other objects are achieved in accordance with the invention -by connecting the voltage output terminals of a single ballast across the serially connected sets of lamps. Heater lwindings are provided for the lamps and are individually connected to the lamp filaments or cathodes. Switches are respectively connected in parallel with each Iset of lamps. The set of lamps having an open switch is energized through the other closed switches by the single ballast so that the lamp sets can be energized or ashed o'n in any desired sequence by a proper operation of the switches.

The invention is particularly pointed out in the claims. The invention may be better understood by the following description given in connection with the accompanying drawing comprising a single figure that shows one preferred embodiment of a system in accordance with the invention.

The embodiment shown in the single figure includes Y switch A is closed, lamp set B is 3,351,809 Patented Nov. 7, 1967 three sets A, B, and C of fluorescent lamps, each set comprising three lamps. The lamps are typical fluorescent lamps having a cathode or filament at each end. Lamp set A comprises lamps LAI, LA2, and LA2. Lamp set B comprises lamps LBI, LB2, and LB3. Lamp set C comprises lamps LCI, LC2, and LC3. While only three sets of lamps have been shown, each set having three lamps, it is to be understood tha-t the system of the invention may be used with more or less sets, and that each set may comprise more or less lamps. The embodiment shown in the figure is only one of many possible embodiments.

The lamps are energized from a suitable source of alternating current, such as volts, 60 cycles. A ballast transformer (enclosed in dashed lines) is provided and comprises a primary winding P, two secondary windings SI, S2, and a power capacitor 22. The secondary windings SI, S2 are split as shown in order to hold the maximum secondary voltage to input line voltage to the lowest possible ratio. The primary Winding P and the secondary windings SI, S2 are connected in autotransformer or voltage adding relation as indicated by the polarity dots adjacent eac'h winding. The windings are coupled to a suitable ballast core, such as a shell-type core. lThe power capacitor 22 is coupled in series with 'one of the secondary windings. The power capacitor 22 provides power factor correction and may provide ballasting. In addition, the core of the ballast transformer may be provided with suitable shunt paths to provide the needed leakage reactance of a ballast transformer. The output voltage of the ballast transformer is provided at the upper terminal of the capacitor 22 and the lower terminal of the secondary winding S2.

This output voltage is coupled to or applied across the serially connected sets of lamps. Specifically, the capacitor 22 is coupled to one side of the upper cathode of the lamp LAI, and the lower end of the secondary winding S2 is coupled to one side of the lower cathode of the lamp LC3. The intermediate cathodes of each set of lamps are coupled together. For example, the lower cathode of the lamp LAI is coupled to the upper cathode of the lamp LA2, and the lower cathode of the lamp LA2 is coupled to the upper cathode of the lamp LA3. And the sets are coupled in series so that there is a series path through the three sets of lamps. Thus, there is a connection between one side of the lower cathode of the lamp LA3 and one side of the upper cathode of the lamp LBI, and a connection between one side of the lower cathode of the lamp LBS and one side of the upper cathode of the lamp LCI. Three switches A, B, and C, each having open and closed positions, are respectively coupled in parallel across each of the sets of lamps. Thus, the switch A is coupled between the upper cathode of the lamp LAI and the lower cathode of the lamp LA3. The switch B is coupled between the upper cathode of the lamp LBI and the lower cathode of the lamp LB3. And the switch C is coupled between the upper cathode of the lamp LCI and the lower cathode of the lamp LCS.

As will be explained in greater detail, when the lamp cathodes are energized by heater transformers, the lamps may be energized or turned on by one switch being open and the other switches being closed. Thus, if it is desired to energize or turn on lamp set A, the switch A is opened and switches B and C are closed so that the output voltage of the ballast transformer is applied to the lamp set A. Then, if another switch, such as switch B is opened and energized. The lamps may be energized or turned on in any sequence or order desired. As previously mentioned, any number of lamps may be provided in each set, and any number of sets may be provided. Such additional lamps or sets would be coupled in series as shown in the figure. Of course, if a larger number of lamps was to be energized or turned on at any given time, the output voltage of the ballast transformer would have to be increased accordingly.

The cathodes or filaments of the various lamps are energized at all times by respective heater transformers A, B, and C (shown enclosed in dashed lines). The heater transformers comprise primary windings PA, PB, PC which are coupled to the alternating current source. Each of the heater transformers comprises four isolated secondary windings for connection to the cathodes or filaments of each set of lamps. Thus, with respect to the heater transformer A, the secondary winding SAI is coupled across the upper cathode of the lamp LAI, the secondary winding SA2 is coupled across the connected cathodes of the lamps LAl and LA2, the secondary winding SA3 is coupled across the connected cathodes of the lamps LA2 and LA3, and the secondary winding SA4 is coupled across the lower cathode of the lamp LA3. Similar connections are made between the heater transformer B and the lamp set B, and between the heater transformer C and the lamp set C. The size or power handling capability of the heater transformers is related to the cathode or filament current required. For example, the secondary windings SAl and SA4 may be made smaller than the windings SA2 and SAS.

Each of the heater transformers comprises two start capacitors. These capacitors are connected between a common point on an outer secondary winding and the two inner secondary windings. In heater transformer A, start capacitors 10, 12 are connected between the secondary winding SAI and the secondary windings SA2 and SA3 respectively. Similar connections are provided with start capacitors 14, 16 in the heater transformer B, and with start capacitors 18, 20 in the heater transformer C. If the switch A is opened and switches B and C are closed, the lamp set A will be energized and turned on. With the output voltage of the ballast transformer applied across the lamp set A, the lamp LA3 receives substantially all of this output voltage because of the low impedance path of the starting capacitors 10, 12. When the lamp LA3 is lighted or turned on, the output voltage is then applied to the lamp LA2. When the lamp LA2 is turned on, the output voltage is then applied across the lamp LA1. However, the output voltage may, for a given set of lamps, be sufficient so that starting capacitors are not needed. With the switch B or C open and with the other switches closed, the lamp set B or the lamp set C may be similarly energized and turned on. In all cases, there is no delay in the turning on because the cathodes or filaments are constantly energized.

It will thus be seen that the invention provides an irnproved lamp energizing or iiashing system which requires only a single ballast transformer and one or more relatively simple heater transformers. With the heater transformer arrangement of the invention, all of the lamp filaments or cathodes are energized at all times, so that when a set of lamps is to be turned on by the appropriate opening and closing of switches, the set of lamps to be turned on is turned on very quickly since its cathodes are all preheated. It is not necessary that the heater windings of a conventional ballast have time to heat the cathodes and then turn the lamps on. In addition, the invention requires only a single ballast transformer. Thus, the invention provides a relatively simple, low cost, flexible, and a rapid lamp energizing system. Therefore, while the invention has been described with reference to one particular embodiment, it is to be understood that modifications may be made without departing from the spirit of the invention or from the scope of the claims.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A system for individually energizing at least one set of a plurality of sets of gaseous discharge lamps having cathodes connected between input terminals to provide la series path therethrough, each of said sets comprising at least one lamp, said system comprising: a main ballast transformer having a magnetic core, a primary winding, and a secondary winding coupled to said magnetic core and connected in autotransformer relation between output terminals to produce an output voltage thereacross; a plurality of heater transformer means each having input terminals and a plurality of output terminals; input leads for connection to a source of alternating current; means coupling said primary winding of said main ballast transformer across said input leads; means coupling said input termin-als of said heater transformer means across said input leads; means respectively coupling the output terminals of each of said plurality of heater transformer means to cathodes of the lamps in a selected set; means coupling said output terminals of said ballast transformer to said input terminals of said serially connected sets of lamps for applying said output voltage thereto; a plurality of switching means each having an open position and a closed position respectively coupled across each of said sets of lamps and selectively activated to provide for energization and deenergization of individual sets of said plurality of sets of lamps so that said output voltage of said main ballast transformer is applied to the set of said lamps coupled to an open switching device.

2. The system of claim 1 wherein said heater transformer means comprises at least one primary winding coupled to said input terminals and =a plurality of secondary windings respectively coupled to said output terminals.

3. A system for individually energizing one of N serially connected sets of gaseous discharge lamps, each of said lamps having cathodes, where N is any integer greater than one, each of said sets comprising at least one serially connected lamp, said system comprising: a main ballast transformer having a magnetic core, a primari winding and a pair of secondary windings coupled to said magnetic core, means connecting said secondary windings to opposite ends of said primary winding in autotransformer relation to produce an output voltage, a power capacitor coupled in series with said connected windings; N heater transformers each having a magnetic core, a primary winding and a plurality of heater windings coupled to said core; input leads for connection to a source of alternating current; means coupling said primary winding of said main ballast transformer across said input leads; means coupling each of said primary windings of said heater transformers across said input leads; means respectively coupling said heater windings to said cathodes of said lamps; means coupling said ballast transformer to the ends of said serially connected sets of lamps for applying said output voltage thereto; N switching devices each having an open position and a closed position; and means respectively coupling said switching devices across each of said sets of lamps so that said output voltage of said main ballast transformer is applied `to the set of said lamps having a switching -device in said open position.

4. The system of claim 3` wherein each of said heater transformers comprises at 'least one starting capacitor coupled between two of said heater windings.

References Cited UNITED STATES PATENTS 2,394,966 2/ 1946 Floyd 315-97 2,719,937 10/1955 Keitfer 315-97 3,176,187 3/1965 Sola 315-97 3,240,993 3/'1966 'Bell 315-100 I OHN W. HUCKERT, Primary Examiner.

J. D. CRAIG, Assistant Examiner. 

1. A SYSTEM FOR INDIVIDUALLY ENERGIZING AT LEAST ONE SET OF A PLURALITY OF SETS OF GASEOUS DISCHARGE LAMPS HAVING CATHODES CONNECTED BETWEEN INPUT TERMINALS TO PROVIDE A SERIES PATH THERETHROUGH, EACH OF SAID SETS COMPRISING AT LEAST ONE LAMP, SAID SYSTEM CONPRISING: A MAIN BALLAST TRANSFORMER HAVING A MAGNETIC CORE; A PRIMARY WINDING, AND A SECOND WINDING COUPLED TO SAID MAGNETIC CORE AND CONNECTED IN AUTOTRANSFORMER RELATION BETWEEN OUTPUT TERMINALS TO PRODUCE AN OUTPUT VOLTAGE THERACROSS; A PLURALITY OF HEATER TRANSFORMER MEANS EACH HAVING INPUT TERMINALS AND A PLURALITY OF OUTPUT TERMINALS; INPUT LEADS FOR CONNECTION TO A SOURCE OF ALTERNATING CURRENT; MEANS COUPLING SAID PRIMARY WINDING OF SAID MAIN BALLAST TRANSFORMER ACROSS SAID INPUT LEADS; MEANS COUPLING SAID INPUT TERMINALS OF SAID HEATER TRANSFORMER MEANS ACROSS SAID INPUT LEADS; MEANS RESPECTIVELY COUPLING THE OUTPUT TERMINALS OF EACH OF SAID PLURALITY OF HEATER TRANSFORMER MEANS TO CATHODES OF THE LAMPS IN A SELECTED SET; MEANS COUPLING SAID OUTPUT TERMINALS OF SAID BALLAST TRANSFORMER TO SAID INPUT TERMINALS OF SAID SE- 